How can I storing the IEnumerator with parameters?

IEnumerator some_funcion;

void Start(){
        some_function = IEnumerator_function();
        }

public IEnumerator IEnumerator_function(bool x){
         //doing something
        }

Help~how can make it works. Thankyou for your suggestion~

// Variable type must be of IEnumerator
private IEnumerator some_function;

void Start() 
{
    some_function = IEnumerator_function(true); // or false
}

// See how return type here is IEnumerator
public IEnumerator IEnumerator_function(bool x)
{
    // execute
}